The Harford County Sheriff's Office (HCSO) is the largest sheriff's office in Maryland and is the primary law enforcement agency servicing a population of 241,402 persons within 440.35 square miles (1,140.5 km2) within Harford County, MD.
The HCSO was created on March 22, 1774 after an act of the Maryland General Assembly in 1773 as Baltimore County was divided in half creating the new county of Harford. Thomas Miller was appointed the first Sheriff by the Lord Proprietor of the Province, Henry Harford (the county's namesake). Although initially appointed, all subsequent Sheriffs were elected to two-year terms until 1914 when the term was extended to four years.
The current Sheriff is Jeff Gahler. The HCSO employs over 500 sworn and civilian support staff and has three basic duties: general law enforcement, court-order enforcement, and correctional services. The HCSO also has a myriad of special operations such as K-9, SWAT, and Accident Investigation among others.
In 2013, the Sheriff's office opened an aviation unit with the granting of a Bell OH-58 helicopter. In 2015 the aviation program was discounted.